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tdutils/td/utils/List.h

@@ -0,0 +1,104 @@
+/*
+    This file is part of TON Blockchain Library.
+
+    TON Blockchain Library is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    TON Blockchain Library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with TON Blockchain Library.  If not, see <http://www.gnu.org/licenses/>.
+
+    Copyright 2017-2019 Telegram Systems LLP
+*/
+#pragma once
+
+#include "td/utils/common.h"
+
+namespace td {
+
+struct ListNode {
+  ListNode *next;
+  ListNode *prev;
+  ListNode() {
+    clear();
+  }
+
+  ~ListNode() {
+    remove();
+  }
+
+  ListNode(const ListNode &) = delete;
+  ListNode &operator=(const ListNode &) = delete;
+
+  ListNode(ListNode &&other) {
+    if (other.empty()) {
+      clear();
+    } else {
+      ListNode *head = other.prev;
+      other.remove();
+      head->put(this);
+    }
+  }
+
+  ListNode &operator=(ListNode &&other) {
+    this->remove();
+
+    if (!other.empty()) {
+      ListNode *head = other.prev;
+      other.remove();
+      head->put(this);
+    }
+
+    return *this;
+  }
+
+  void connect(ListNode *to) {
+    CHECK(to != nullptr);
+    next = to;
+    to->prev = this;
+  }
+
+  void remove() {
+    prev->connect(next);
+    clear();
+  }
+
+  void put(ListNode *other) {
+    other->connect(next);
+    this->connect(other);
+  }
+
+  void put_back(ListNode *other) {
+    prev->connect(other);
+    other->connect(this);
+  }
+
+  ListNode *get() {
+    ListNode *result = prev;
+    if (result == this) {
+      return nullptr;
+    }
+    result->prev->connect(this);
+    result->clear();
+    // this->connect(result->next);
+    return result;
+  }
+
+  bool empty() const {
+    return next == this;
+  }
+
+ private:
+  void clear() {
+    next = this;
+    prev = this;
+  }
+};
+
+}  // namespace td